Wristwatch with means for checking radioactivity of the environment

ABSTRACT

A WRISTWATCH PROVIDED WITH MEANS FOR CHECKING THE RADIOACTIVITY OF THE ENVIRONMENT IN WHICH THE WATCH IS OF THERMO-LUMINESCENT MATERIAL, THE THERMO-LUMINESCENCE LOCATED, THE CHECKING MEANS COMPRISING AN ELEMENT MADE   OF WHICH VARIES WITH THE RADIATIONS TO WHICH THE ELEMENT HAS BEEN SUBMITTED.

F. WRISTWATCH WITH MEANS FOR CHECKING RADIOAGTIVITY March 16, 1971CHARLES OF THE ENVIRONMENT Filed May 13, 1969 FIG. 3

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United States Patent 3,570,239 WRISTWATCH WITH MEANS FOR CHECKINGRADIOACTIVITY OF THE ENVIRONMENT Francois Charles, Bassecourt,Switzerland, assignor to Georges Ruedin S.A., Bassecourt, Bern,Switzerland Filed May 13, 1969, Ser. No. 824,155 Int. Cl. G04b 37/12U.S. Cl. 58-152 4 Claims ABSTRACT OF THE DISCLOSURE A wristwatchprovided with means for checking the radioactivity of the environment inwhich the watch is located, the checking means comprising an elementmade of thermo-luminescent material, the thermo-luminescence of whichvaries with the radiations to which the element has been submitted.

The present invention has for an object the provision of a watch,especially a wristwatch, characterized by the fact that it is providedwith means for checking the radioactivity of the environment in whichthe watch is located.

In the. drawing:

FIG. 1 is a plan view of a first embodiment of a wristwatch, and

FIGS. 2 and 3 are partial sectional views of two other embodiments ofWristwatches.

The wristwatch represented in FIG. 1 comprises a casing 1 and a dial 2,this latter occupying only a portion of the upper surface of the casing.

The wristwatch shown includes a device for measuring radioactivitycomprising a circular pellet 3 disposed in the portion of easing 1 notoccupied by dial 2, the pellet being made of a thermo-luminescentmaterial such, for example, as lithium fluoride, capable of reacting toradioactivity; that is to say, it is formed of crystalline material theluminescence of which varies with the radiations to which this materialhas been submitted.

The crystalline material of the pellet produces luminescence whenheated. The degree of luminescence produced is determined by theduration and intensity of the radiations to which the material has beenpreviously submitted.

The pellet 3 is releasably contained in a circular recess provided onthe upper face of the casing, 50 that the user of the watch can,periodically, replace this pellet by a new one and check theluminescence of the old one by heating the pellet and then measuring itsluminescence.

This luminescence being a function of the radiations to which thematerial has been submitted, its measure permits the user of the watchto determine if he has or has ice not been exposed to such radiationsand, if so, to what extent.

In the embodiment of FIG. 2, the watch includes a ring 4 made of athermo-luminescent material sensible to the radiations, engaged into anannular groove 5 provided in the upper face of the watch-case 6. Thebezel 7, snap fitted on the watch-case '6, covers and conceals theannular ring 4 made of thermo-luminescent material.

The user of the watch must, periodically, dismantle the bezel 7 topermit access to the ring of thermo-luminescent material 4 so as tochange it and permit the used ring to be checked.

In the embodiment of FIG. 3, the thermo-luminescent material sensible tothe radiations constitutes a ring 8 which functions as a tighteninggasket interposed between the watch-case 9 and the bottom 10.

In this embodiment, in order that the ring 8 may be checked, it isnecessary to disassemble the bottom and replace the ring 8 with a newone.

As another modification, the material sensible to the radiations may belocated in a recess provided in the outer face of the bottom, closed bya removable cover.

As still another variation, the material sensible to the radiationscould also be carried by the wristwatch strap.

What I claim is:

1. A watch, especially a wristwatch, provided with checking means forchecking the radioactivity of the environment in which the watch islocated comprising a ring of thermo-luminescent material placed on thewatch case and concealed by the bezel removably secured to the watchcase.

2. A Watch as claimed in claim 1, wherein the thermo luminescence varieswith the radiations to which the Watch is submitted.

3. A watch as claimed in claim 2, wherein the dial occupies only aportion of the upper surface of the Watch case and at least a portion ofthe rest of this surface is occupied by the ring of thermo-luminescentmaterial.

4. A watch as claimed in claim 2, wherein the ring of thermo-luminescentmaterial comprises a tightening gasket interposed between two elementsof the watch-case.

References Cited UNITED STATES PATENTS 3,254,219 5/1966 Finlay et al250-83 RICHARD R. WILKINSON, Primary Examiner E. C. SIMMONS, AssistantExaminer US. Cl. X.R 25083; 58-91

